Field of the Invention
The present invention relates to an independent suspension system of a drive wheel in which the drive wheel is vertically swingably supported by a vehicle body frame via a lower arm, an upper arm disposed over the lower arm, and a cushion unit, which is provided between the vehicle body frame and the lower arm.
Description of Related Art
Such an independent suspension system is generally already known, as shown by Japanese Patent No. 4467054.
However, in the system disclosed in the above Japanese Patent No. 4467054, a lower arm is configured to have a pair of arm parts having base end parts swingably supported by a vehicle body frame at positions separate from each other in the front-rear direction. Furthermore, an upper arm is composed of an arm member having a base end part swingably supported by the vehicle body frame and an upper sub-arm swingably joined to a tip part of the arm member. Moreover, a cushion unit is provided between the front arm part in the pair of arm parts of the lower arm and the vehicle body frame. Thus, not only a complicated structure but also increase in the weight is caused. In addition, the space for disposing the cushion unit is comparatively large.